Stencil sheet and method of making the same



Patented June 11, 1935 STENCIL SHEET AND METHOD OF MAKING THE SAME LouisG. Brandt, Portsmouth, Va.,, assignor to The Multistamp Company, Inc.,Norfolk, Va., a corporation of Virginia No Drawing. Application May 3,1932, Serial No. 609,046. Renewed November 15, 1934 9 Claims. (01.41-53815) This invention relates to stencil sheets, which, as is Wellknown, are universallymade from sheets of Yoshino paper coated with acomposition which is type-impressible, so that the sheet may be put in atypewriter and after receiving the impression of the type, may beremoved and placed over an inked pad, the ink from which seeps throughthe narrow apertures cut in the coating composition by the type and thusreproduces, on a sheet of paper, the message typed out. Such sheets havebeen in use for perhaps fifty years, and many different compositionshave been proposed and used with more or less success. The leastexpensive stencil sheets, today as for the past forty or fifty years,are coated by a composition made largely from paraffin, but as they willyield only about 50 or '75 copies, wax stencils are little used.Stencils made of protein (gelatin) were extensively used ten to fifteenyears ago,but as such sheets hadto be moistened, and moisture wasinjurious to typewriters, besides causing a loss of time, they werenever considered wholly satisfactory. The introduction of anitrocellulose stencil, about 1925, caused practically a discontinuanceof protein or wet stencils; and today probably of all stencil sheetsused in this country are of a nitrocellulosic composition, usuallysoftened with vegetable or mineral oils or fatty acids, such as stearicacid.

There are two very serious drawbacks to nitrocellulose stencils: first,that they deteriorate, slowly but surely, althoughvery rapidly ifexposed to a little heat; second, that they are expensive.

A sheet 18" x 25" may cost, in wholesale lots, about nine cents, towhich must be added various manufacturing costs, overhead, packing andshipping expense, sales expense, allowances for spoilage, returns, etc.The result is that the retail price for stencil sheets is too high formany people to bear. School teachers, for example,

have need, many times a day, of a stencil sheet, so thatevery member ofeach class may be given instructions, quizzes, etc.; but because of thehigh cost of stencil sheets of the better class, and the highlyunsatisfactory nature of the poorer grades of stencil sheets, the use ofstencil duplicators has never attained anything like the proportionswhich it should in American schools. It is not too much to say thatthere is an imperative demand for an extremely cheap stencil sheet whichwill be capable of making hundreds, or even thousands, of clear copies.The present invention makes possible the production of such a stencilsheet. 7

In accordance with the invention, and as one illustrative exampleof themanner in which. the invention may be practiced, I take 13 gm. ofprotein (gelatin) and add 10 oz. of clean water, heating to 212 F. Thegelatin, of course, dissolves, to make solution No. 1. Then I take 1.5oz. of pure soap of almost any composition (one example being Ivorysoap) and 10 oz. of clean water, boiling to make solution No. 2. Then Icompound the two solutions at 212 F., and add 3 gm. of any water solubledye of the desired color. The inexpensive'dyes which are used to colorEastereggs are entirely suitable, I have found.

Stirring is continued for some time to insure complete dissolving and.uniform mixing of the dye. Cooling is thenpermitted, to about 150 F.,when I add, to the above-described mixture, 1 oz. of almond oil and 1oz. of pure glycerin (or I may use 2 oz. of almond oil instead) and mixthoroughly. When the mixture has cooled to -90 F., it may be applied toa sheet of Yoshino paper in any suitable way, and the coated sheetshould then be hung up to dry at ordinary room temperatures. Afterdrying is sufliciently complete, I dip the coated sheet in a 15%solution of formaldehyde, thus coagulating the gelatin to make itwaterresistant, and then hang up the sheet again to dry at roomtemperatures. The sheet is now ready for packaging or storing. g

Stencil sheets made as described will cost only about one cent per 18 x25" sheet, or only oneninth of the cost of nitrocellulose sheets of aquality scarcely superior. Experiments show that upwards of 4000 legiblecopies may be made from a single stencil sheet. Thus the two desideratamentioned above are fully realized by the invention.

However, the invention has other important aspects. First, the stencilsheets are substantialchanges: an important improvement when it isrecalled that the cheap wax stencils and the expensive nitrocellulosestencils'are both ruined by a little heat, such as will be found near aradiator. Secondly, the sheets will Stand considerable handling, withoutinjury, whereas wax stencils will not. Thirdly, there is nodeterioration: thec'omposition used is inert and is non-hygroscopic,non-hardening, non-softening. Fourthly, the raw materials used are allreadily available almost anywhere, in unlimited quantities, at lowprices. Fifthly, the sheets withstand packing, pressure, rolling,storage, shipping and other commercial treatment, without injury tothemselves or to anything with which they come in contact, either beforeor during use. Thus the importance of the advance I have made in the artwill be apparent.

Obviously, the invention may have various embodiments, provided they arewithin the scope of the appended claims. For example, I may use manyoils and oil compounds in place of the almond oil mentioned above.

Having described a preferred embodiment of the invention and the bestmanner now known to me of practicing the invention, what I claim as newand desire to secure by Letters Patent of the United States of Americais:-

1. A stencil sheet comprising a sheet of Yoshino paper coated with acomposition comprising coagulated, water-resistant gelatin, soap and anoil, present in the following approximate proportions by weight: 13:4256, respectively.

2. A stencil sheet consisting of a sheet of Y0- shino paper coated witha composition made from the following ingredients: 13 gm. of coagulatedwater-resistant gelatin, 1.5 oz. of pure soap, and 2 oz. of an oilytempering agent.

3. A stencil sheet consisting of a sheet of Y0? shino paper. coated witha composition made from the following ingredients: 13 gm. of coagulated,water-resistant gelatin, 1.5 oz. of pure soap, and .302. of almond oil.

4. A stencil sheet consisting of a sheet of Y0- shino paper coated witha composition compris ing :13 gm. of coagulated, water-resistantgelatin, 1.5 02.01 pure soap, 3 gm. of water-soluble dye, 2 oz. of oil.

5. A stencil sheet consisting of a sheet of Y0- shino paper coated witha composition comprising 13 grrnof coagulated, water-resistant gelatin,1.5 oz. of pure soap, 3 gm. of water-soluble dye, 1 oz. of oil and 1 oz.of glycerin.

6. That method of making a composition for coating stencil sheets whichcomprises preparing an aqueous solution of gelatin, preparing an aqueoussoap solution, compounding the two solutions; and finally adding an oilytempering agent in sufficient quantity to at least equal the amount ofsoap and gelatin present in the solution.

'7. That method of making a composition for coating stencil sheets whichcomprises the making of a protein solution from 13 gm. of gelatin andoz. of water; heating said solution to 212 F.; making a soap solutionfrom 1.5 oz. of soap and 10 oz. of water and heating the soap solutionto 212 F.; compounding the two solutions; allowing the mixture to coolsomewhat and adding a quantity of oil about equal to the amount of drysoap and gelatin present in the solution and finally cooiing to below100 F.

8. A stencil sheet comprising a sheet of Y0- shino paper coated with acomposition comprising coagulated, water-resistantgelatin, soap and anoil; theproportion by weight of soap being over three times that of thegelatin, and the proportion by weight of oil materially exceeding thatof the soap.

9. A stencil sheet comprising a sheet of Yoshino coated with acomposition comprisin coagulated, water-resistant gelatin, soap andamixture of an oil and glycerin in substantially equal parts; proportionby weight of the soap being over three times that of the gelatin, and

L. G. BRANDT.

